same issue for me as well. i read all of the comments and i can say that the problem is pretty much the same. left air trigger works well but the right one flickers for the most users. i've been using this phone like 7 months. it's been a while since the latest update, so i do not think that it's related to the update issue. it suddenly started just a few days ago. i also formatted the phone but the problem is still active. i cleared the surface of the buttons, tried sensitivity booster etc... nothing works... it makes me extremely annoying because i've been using it for 7 months in FPS games. and because of that i used to it, it's a big problem for me... i hope it'll be solved otherwise my next phone will not be an Asus. And please let me know if any of you guys find a solution.
Edit: i just added the video of it. as you can see in the video, the left air trigger is completely fine when i move my fingers on the surface. but the right one flickers all the time. the result is the same if i hold my fingers on the right air trigger.